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Silverado Heating - All Hot

Hi Everyone,

I’ve got a 2004 Silverado 2500, crewcab, longbed with a 8100cc gas engine. The truck has 80,000 miles and is in great condition. There’s just one little problem - the climate cntrol system will occassionally go to completely hot. When it started a couple years ago, it was weeks between occurences. Now it’s about every day and can be multiple times a day. When the system goes to hot, the only way to get back to the proper setting is to turn off the ignition and then restart.

It was happening on both the driver and passenger sides, but the first attempt to repair this issue was to change the envirenmental control computer - now the heat only happens on the driver side. The passenger side remains as set.

The repair shop has tried 5 times to fix the issue and is now stumped. Any help would be appreciated.


Does the vent reset when you restart the car like it did before?

If I was working on this I would want to know what the sun sensor signal for the left side shows compared to the right side. The service data shows those signals tie to the BCM so there may be a problem with it. The trouble may also be due to a intermittent problem with the wiring to left side vent. There are also left and right air temperature sensors signals that should be checked for a signal level problem.

When we restart the truck, the system almost always goes back to normal (how the controls are actually set). There have been a few times when the truck starts up on the “hot” condition, but we cannot tell if it started that way or just flipped to hot within a minute or so.

Thanks for the tip. I’ll ask the repair shop if they checked the sun sensors and wiring. The last thing they tried was to take the entire dash out and check every connector, but I’ll ask about the sensors specifically.